Pest Alert: Spotted Wing Drosophila


We have started to detect SWD in blueberry and raspberry crops here in Durham and suspect that most fruit growing areas will be at low to high risk of infestation in the following weeks.

Spotted Wing Drosophila (SWD) is a vinegar gnat from China and Japan. It attacks ripening and ripe fruit of brambles (raspberry & blackberry), strawberry, blueberry, grape, cherry, plum and peach, plus many species of wild berries. We first discovered it in New Hampshire on September 6, 2011. In 2012, SWD caused over $1.5 million in crop losses in NH. If you wish to keep your fruit from becoming infested, it is critical to monitor the insect with traps. When the flies appear and your crop is ripening, an insecticide spray can prevent it from being infested. Other cultural practices are important, like frequent harvesting during periods of high risk and refrigerating fruit after harvest.

There are several landscape factors that influence the SWD populations in your neighborhood, so trapping at your own farm is the best way of knowing what is happening in your crop and will help you make the most effective management decisions.